An exposure apparatus such as a stepper, a scanning stepper or the like, which is used, for example, in the lithography step in order to produce an electronic device (microdevice) such as a semiconductor element or the like, is provided with an illumination optical system for illuminating a reticle (mask) under various illumination conditions and at uniform illuminance distributions. The conventional illumination optical system has been provided with an intensity distribution setting optical system having a plurality of exchangeable diffractive optical elements in order that the light intensity distribution, which is provided on the pupil plane of the illumination optical system (plane conjugate with the exit pupil), is set to a distribution in which the intensity is increased, for example, in a circular area, an annular area, or a multipole area depending on the illumination condition.
Recently, an illumination optical apparatus which is provided with an intensity distribution setting optical system is also suggested. The intensity distribution setting optical system utilizes a spatial light modulator of the movable multi-mirror system having a large number of minute mirror elements with variable angles of inclination so that the shape of the light intensity distribution on the pupil plane of the illumination optical system (hereinafter referred to as “pupil shape”) can be optimized to various distributions, depending on the pattern of the reticle (see, for example, U.S. patent application Publication No. 2003/0038225).